Field of the Invention
This invention relates to a new and distinct variety or cultivar of the deciduous tree Ulmus parvifolia, commonly known as the lacebark elm.
Description of the Related Art
Lacebark elm, Ulmus parvifolia, was originally given the common name Chinese elm. Unfortunately, this common name was confusingly similar to the common name of Ulmus pumil, the Siberian elm. Because of the frequent confusion resulting from the similarity of these common names, Mr. E. W. Johnson of the U.S. Department of Agriculture and of Woodward, Okla. began referring to Ulmus parvifolia as lace-bark elm. Mr. Johnson used the common name lace-bark elm for Ulmus parvifolia in his writings on the introduction and study of trees for windbreaks: Ornamental and Windbreak Trees for the Southern Great Plains, USDA Crops Research Bulletin ARS 34-77 (1966). In 1973, the inventor of the present new cultivar began using and promoting the common name lacebark elm in his many writings as a substitute for the less suitable name Chinese elm. The name lacebark elm is now nearly universally accepted as the common name.
The lacebark elm is native to northern and central China, extending eastward into Korea. Typically, the lacebark elm is a large tree that matures to between about forty and about fifty feet tall and about the same dimensions wide. The lacebark elm is very adaptable to poor soil conditions and may be further characterized as having leaves that are dark green and having bark that is attractive.
The original seed from which this new cultivar is a descendent was collected south of Sian, China in 1914 and sent to the United States by U.S.D.A. plant explorer Frank N. Meyer. The resulting seedlings contributed to the Prairie State Forestry Project between 1935 and 1942 and the resulting 17,000 mile shelterbelt system. According to Mr. Johnson, at least a portion of the seed sent by Meyer ended up at the U.S.D.A. Southern Great Plains Field Station in Woodward, Okla. Mr. Johnson noted in 1966 that growth of Ulmus parvifolia seedlings was quite variable and that small leaved selections were typically more cold and drought tolerant.
The original seed used to develop this new cultivar was obtained by the inventor in 1972 from a large lacebark elm tree with small, glossy leaves located at the home of Mr. E. W. Johnson in Woodword, Okla. This large lacebark elm tree was grown from the seed sent back from Sian, China in 1914. The inventor also took cuttings from Mr. Johnson's tree on three occasions, but none rooted. However, thousands of lacebark elm seedlings were grown from those original seeds collected in 1972 from Mr. Johnson's tree.
By 1984, thirteen outstanding tree seedlings had been selected from all those grown from the seeds collected in 1972. However, each of these thirteen selections responded quite differently to attempts to propagate them from cuttings. No cuttings were ever rooted from 3 of the thirteen selections and these selections were discarded. Five selections rooted poorly, generally with a success rate of less than 25%, so these selections were also discarded. The five selections that rooted the best were studied in detail by Gary G. Hickman and the inventor. Of these five, only two grew moderately well following rooting of the cuttings, but the growth form of the offsprings from these two selections required considerable pruning and training at an early age to make desirable trees resembling the parents. These selections were judged to require excessive work to develop into desirable tree forms, so these selections were also discarded.
In 1984, the inventor wrote in his book entitled Plant Production In Containers, Lacebark Publications, Stillwater, Okla. (1984, 1988, 2003): “This study leaves little doubt about great differences among individual seedlings to root and grow into useful plants. If an outstanding tree is located, the first step is to determine if it will root from cuttings. The second step is to evaluate the growth and form and quality of the rooted cuttings. If the tree fails on either evaluation, look for other trees of the same species with good qualities and continue. Just because one tree of a species does not root or grow well does not mean that another specimen will respond the same way.”
In 1988, seeds were collected from a desirable lacebark elm in Stillwater, Okla. that had resulted from the seeds collected in 1972 from the large lacebark elm tree of Mr. Johnson in Woodward, Olka. These seeds were planted, resulting in approximately sixty lacebark elm trees. The inventor then collected seeds from the two best specimens of these sixty lacebark elm trees and planted them in containers, resulting in approximately 2,000 tree seedlings. The most desirable of these seedlings, about 800, were selected and planted into the field for further evaluation. In the fall of 1996, seeds were collected by the inventor from two of these 800 trees, chosen for their demonstrated exceptional growth. The collected seeds from these two trees were planted, resulting in about 2800 seedlings. The inventor evaluated these seedlings, culling out the undersirable ones until only the best nine seedlings remained. These seedlings were characterized as having small leaves, exceptional vigor, a central leader and good form.
In February, 2002, when the nine selected trees were about 12 feet tall with a 3 inch stem diameter at the base, a severe ice storm occurred. Only one tree survived this ice storm with no damage and still standing upright, while the other eight trees were severely bent over and suffered broken limbs as a result of the ice. Then again in February, 2003 the nine trees were subjected to an even more severe ice storm and the same one tree, the new cultivar of the present invention, remained upright with no damage. One of the nine trees broke off near the ground as a result of the ice storm and the other seven trees were severely bent over and suffered broken limbs.
This new and distinct plant was asexually reproduced by rooting softwood cuttings taken from the original plant near Stillwater, Olka. The asexually reproduced plants show the unique features that characterize this new lacebark elm tree indicating that the unique features of this plant are stable through its successive generations of asexual reproduction. Furthermore, the asexually reproduced offspring grow with exceptional vigor and with a strong central leader stem unlike any before experienced by the inventor.